Objectives are (1) to explore the role of the renin-angiotensin system in experimental and clinical hypertension, using specific radioimmunoassay techniques for angiotensin II, angiotensin I, renin activity and renin substrate concentration. (2) To isolate and define the physiological role of proteins found in normal plasma which are immunologically related to angiotensin I and angiotensin II. (3) Using specific anti-angiotensin antisera and immunochemical methodology to define the role of the renin angiotensin system in acute oliguric renal failure. (4) To standardize diagnostic techniques for renovascular hypertension and primary hyperaldosteronism.